99.asm

是完成从００到９９计数的汇编程序生成文件

       SECOND EQU 30H
       TCOUNT EQU 31H
       ORG 00H
       LJMP START
       ORG 03H
       LJMP PRESS
       ORG 0BH
       LJMP CLOCK
START: MOV SECOND,#00H
       MOV TCOUNT,#00H
       MOV R7,#00H
       MOV TMOD,#01H
       MOV TH0,#(65536-50000)/256
       MOV TL0,#(65536-50000) MOD 256
       SETB EA
       SETB EX0
       SETB ET0
       SETB PX0
       SETB  IT0              
DISPLAY: ACALL DISP
         SJMP DISPLAY        ;主程序结束
DISP:   MOV A,SECOND         ;显示子程序
        MOV B,#10
	DIV AB
	MOV   P0,#00H
        MOV DPTR,#TABLE
	MOVC A,@A+DPTR
     	MOV P0,A
	MOV A,#0FDH          ;1111 1101
	MOV P1,A
	ACALL DELAY
	MOV   P0,#00H
        MOV A,B
	MOVC A,@A+DPTR
	MOV P0,A
	MOV A,#0FEH
	MOV P1,A
        ACALL DELAY
        RET
DELAY: MOV R6,#10            ;延时子程序
D1:    MOV R5,#124
       DJNZ R5,$
       DJNZ R6,D1
       RET                   ;子程序返回               
PRESS:   CJNE R7,#00H,J1          ;INT0的中断服务程序
         INC R7
	 SETB TR0
	 SJMP BACK
     J1: CJNE R7,#01H,J2
	 CLR TR0
         INC R7
	 SJMP BACK
     J2: CJNE R7,#02H,BACK
	 MOV R7,#00H
	 MOV SECOND,#00H
         MOV TCOUNT,#00H
   BACK: RETI                     ;中断返回 
CLOCK:   MOV TH0,#(65536-50000)/256          ;T0中断服务子程序
         MOV TL0,#(65536-50000)MOD 256
	 INC TCOUNT
	 MOV A,TCOUNT
	 CJNE A,#20,NEXT
	 MOV TCOUNT,#00H
	 INC SECOND
	 MOV A,SECOND
	 CJNE A,#100,NEXT
	 MOV SECOND,#00H
   
   NEXT: RETI                     ;中断返回   
TABLE: DB 3FH,06H,5BH,4FH,66H,6DH,7DH,07H,7FH,6FH
         END